Method of distillation



Oct. 29, 1929. c. P. TOLMAN METHOD OF DI$'l ILLATION Filed Nov. 22, 1924 fl V EN TOR. (Mm/64 A TTORNEYS Patented Oct. 29, 1929 UNITED STATES PATENT OFFICE CHARLES P. TOLMAN, OF KEN GARDENS, NEXV YORK, ASSIGNOR TO PETROLEUM CON- VERSION CORPORATION, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE METHOD OF DISTILLATION Application filed November 22, 1924. Serial No. 751,425.

My invention relates to the distilling or other heat treatment of materials of an organic nature andwill be best illustrated by the following detailed description of its application to the distillation and cracking of mineral oils and other classes of hydrocarbons.

It is well known that the tendency of hydrocarbon compounds to carbonize at slightly above the desired treatment temperatures, even when under considerable pressure, causes a large amount of the stock charged in the cracking apparatus in the petroleum industries to be carbonized and otherwise debased, and so rendered unfit for its most valuable usage. This applies to cracking processes in which the heat at or near flame temperature is directly applied to the shells or tubes containing the petroleum undergoing treatment. The productive capacity of such processes is reduced because the low heat conductivity of petroleum makes it necessary to maintain a less average temperature than is desirable for cracking, in order to reduce the percentage of by-product. Otherwise, because of the low heat conductivity of the petroleum and the limited surface exposed to the shell or tube in proportion to the total volume of the material, the material in contact with such wall would suffer from an excessively high temperature.

It is the purpose of this invention to provide a more suitable and industrially more efficient method for transferring heat from the source of heat to the material under treatment. This is accomplished in this invention by using as the medium of heat transfer a fluid which will not mix with (in the sense of dissolving in) the compounds under treatment, and which will become liquid at or above the final temperature in the system.

The accompanying drawing illustrates my invention, using mercury as the medium for heat transfer in connection with a petroleum cracking process.

The vaporspace of a mercury boiler 10 is connected with a reaction chamber 11 by means of a pipe 12 having a hand valve 13 and a check valve 13 Oil entering the system is forced by means of a pump 14 through pipe 15 equipped with a valve 16, into reaction chamber 11, pipe 15 preferably terminating in a spray nozzle 17. Reaction chamber 11 is preferably provided with a circulating pipe 18 having pump 19 and terminating in a spray nozzle 20 within chamber 11. By this means the oil or other liquid product in chamber 11 may be circulated in a shower therein.

The vapors produced in chamber 11 pass thence through pipe 21 into condenser 22, the condensed products passing from there into a separating chamber 23 through pipe 24. In chamber 23 the mercury and oil separate. For the purpose of returning liquid mercury to the boiler from different points in the system, I provide pipe 25 leading to the liquid space of boiler 10, which pipe 25 is connected with the bottom of chamber 23 through valve 26 and with the bottom of reaction chamber 11 by means of a pipe 27 having a valve 28.

For leading off the condensed oil product from separating chamber 23, I provide a pipe 30 leading to a receiver 31 having a valved olftake 32 for conducting the final product of the system to points of storage or consumption. For withdrawing the non-condensible vapors and gases from the system, I have provided pipe 33 in communication with the top of chamber 23 and preferably provided with relief valve 34. Pipe 33 is connected with the top of receiver 31 through pipe 34 having valve 35. For purposes which will later be apparent, I preferably provide a by-pass 35 leading from the top of chamber 23 into communication with chamber 31, as, for example, by means of a portion of pipe 34 below valve 35. Pije 35 has a valve 35'. In order further to insure that the pressure in separating chamber 23 is the same as that throughout the system, I provide a valved by-pass 36 which, however, is normally closed.

Various gauges and auxiliary apparatus essential to the continued operation of the system are provided, as shown. Among other means for introducing mercury into the system, I have shown a receptacle 37 having valved connections 38 and 39 with vapor pipe 12 and mercury return pipe 25, respectively, as well as a valved funnel connection 40. By

this means and by manipulating the various valves, mercury may be introduced into receptacle 37, the latter place belng under the pressure prevailing in the system and the mercury thus allowed to flow into the boiler through pipe ldercury may also be introduced into the system by means of a valve connection 13 and pump 44: for which is provided a valved by-pass The operation of my improved system will now be readily understood. The boiler 10 and the connecting; system are tilled with mercury to a suitable level, as by use of the funnelled receptacle 3'? or by the other means de scribed. Heat is applied to boiler 10 and the resultant mercury vapor passes under pressure through pipe 12 into reaction chamber 11. At the same time, the oil to be treated is introduced into reaction chamber 11 through pipe 15 and spray nozzle 1?. .ln this manner, the liquid undergoing treatment is sprayed or filmed in chamber 11 am. in such finely divid ed state mingles with the hot mercury vapor. vaporizing}- and cracking of the petroleum takes place and the vapor mixture less such condensation as may take place, passes through pipe 21 into condenser where condensation takes place, the condensate passing through pipe 24 into separating; chamber 23. Here separation of the mercury and oil takes place, the latter being drawn off through pipe 30 into receiver 31. During such transfer. the pressure prevailing in chamber 23 and receiver 31 are equalized byopenint; valve 35" in hy-pass 35". valve 35 in pipe 34 remaining: closed. By means of this arrangement. the oil flows from the two chambers 23 and 31 by gravity. When the transfer has been, made. the valve 30 in pipe 30 and valve 35 in pipe 35 are closed and valve 35 in pipe 341; is opened. to permit the release of gas in receiverSl as well as the evolved from the fluid. in receiver 31 as the pressure diminishes. A pressure gauge 31 on receiver 31 is provided for use in connection with the transt'er. and

the subsequent Freeing; of gas from the flu d transferred. From time to time. receiver 31 is discharpged into suitable receiving tanks through the valved pipe 32. This may be accomplished by gravity. by suitable pumps or by usin the pressure of in the system.

By virtue of hand valve 13 and check valve 18 an excess of pressure in the reaction chamher 11. as tor example. that due to the greater vapor tension of a particular oil undergoing treatment over that of the mercury is prevented from forcing oil vapors back into the mercury boiler. Or, if desired. mercury vapor may be admitted interu'littently by manually operating" valve 13.

Reaction chamber 11 is shown as a single vessel, but. if desired. may be replaced by two or more smaller communicating vessels. Such fluid as is not vaporized. or haviny been vaporized condenses and accumulates in the bottom of chamber 11 below the level of outlet 21, will be returned to the heating zone at the top of the chamber by means of circulating pipe 18 and spray head 20. Such mercury as may condense in reaction chamber 11 may be returned by gravity into the system by means of the valved pipe 27. Similarly the mercury condensing in condenser 22 is returned from the bottom o'l chamber 23 by means of pipe 25. It is desirable that the mercury be returned to the boiler as soon as it condenses. By reason of the location of the different elements of the system, I accomplish such return by gravity. If desired, however, the units may be otherwise arranged and the returnof the mercury accomplished by means of a pump, as, for example, pump It will also be noted that the mercury boiler 10 forming a part of the system constitutes a separate unit which is located apart from the rest of the system whereby the hazard of fire due to the oil bein eignited by heatinc: from the boiler is eliminated.

llly improved method is also adapted for treatment of solid substances of hvdrocarhon nature. such as oil shale. For this purpose. l may provide reaction chamber 11 with Clliiflllll and discharging doors and 51. respectively, it beine; understood that when such solid material is used. the valve 16 in oil suppl pipe 15 will be closed. When operatin with oil shale. the hydrocarbon vaors produced by the heat treatment with the mercury vapor pass from the chamber 11 b means of pipe 21 and are condensed and led from the system in the same manner as has been previously described.

By means of m improved method. I may control with accurac the thermal conditions with n the reaction chamber. whereby'over heatingot the material undergoing heat treatment is avoided.

It is to be observed that the mercury vapor is introduced into contact with the material underoioinot treatment in a saturated condition whereby heat is supplied at the substantially uniform temperature of condensation of this saturated vapor. In this manner the materials undergoing distillation or cracking are subjected to a very even temperature which in the case of the conversion of hydrocarbon oils into motor fuels. for example. is of great importance. A further advantage ot'my method resides in the fact that the presence oi. large quantities of metallic vapor at comparatively high temperatures produces a catalytic effect on the materials underejoinoj treatment. promoting the decomposition of the heavier and the formation of lir hter compounds.

l lhile particularly adapted for the distillation and cracking of hydrocarbon oils and oil shales. my improved method is also applicable to the low temperature distillation of coal, lignite, wood and similar products,

and it is intended to cover broadly its ap plication to the distillation of such products.

I claim 1. In the method of treating hydrocarbon compounds to convert them into compounds of lower molecular weight, the steps which consist in evolving mercury vapor from mercury liquid under conditions producing substantially saturated vapor having a temperature not materially in excess of the desired conversion temperature, introducing said evolved vapor into physical contact with said hydrocarbon compounds in a reaction zone and so proportioning said mercury vapor to said hydrocarbon compounds in said reaction zone as to constitute said mercury vapor the sole source of heat bringing about said conversion reaction, whereby said mercury vapor furnishes said heat at the substantially uniform temperature of its condensation, withdrawing the converted products from said reaction zone and recovering from said products said hydrocarbon compounds of lower molecular weight.

2. In the method of treating petroleum compounds to convert them into compounds suitable as motor fuels, the steps which consist in evolving mercury vapor from mercury liquid under conditions producing a substantially saturated vapor at a temperature not materially in excess of the desired conversion temperature, introducing said evolved vapor into intimate fluid contact with said petroleum in a reaction zone and so proportioning 5 said mercury vapor to said petroleum in said reaction zone as to constitute said mercury vapor the sole source of heat bringing about said conversion reaction whereby said mercury vapor furnishes said heat at the sub stantially uniform temperature of its condensation, withdrawing the converted products from said reacton zone and recovering from said products those suitable as motor fuels. CHARLES P. TOLMAN. 

